1. Field of the Invention
The present invention relates to a data erasing device using permanent magnets. In particular, it relates to a portable data erasing device that can easily erase a hard disk device, used in a computer as a memory device, using permanent magnets.
2. Description of the Related Art
In the prior art, in computers such as personal computers and the like, recording media for recording programs and data have become necessary, and in recent years, hard disk devices using a disk coated with a magnetic material have become popular as such recording media. Such hard disk devices are built into the computer or are used as external hard disk devices connected to the computer via a cable, data being written into at least one internal disk via at least one head. The storage capacity of these types of hard disks has been steadily increasing over the years.
Meanwhile, personal computers are being sold in new formats year by year along with advances in the operating systems that drive them, the processing speed of CPUs (central processing units), the expansion of communication functions, the capacity of hard disk devices, and the like, so that there is a tendency for old personal computers to be replaced with new personal computers within a short period of time.
Hard disk devices built into old computers that have been disposed of when replaced by new computers, and hard disk devices with small memory capacities which have been disposed of when replaced by new hard disk devices with larger memory capacities, still contain large amounts of various types of data which were written into data is data, such as personal information, internal company information and the like, that must not be leaked to a third person. In such cases it is common to perform an erasing process using computer software to erase data on the hard disk device prior to disposal.
However, this data erasing process is simply a process which allows data to be written over regions of the disks in the hard disk device in which data has been previously stored. Consequently, prior art data erasing processes did not completely erase all of the data which had been stored on the disk. Thus, in hard disk devices in which data has not been completely erased in this manner, a third person, using special software, can read the remaining data.
In this regard, as methods for completely erasing data recorded on a hard disk device, methods of forcefully erasing data, such as writing random data on the entire surface of the magnetic disks in the hard disk device or passing the magnetic disks of the hard disk device through a powerful magnetic field such as that generated by a permanent magnet or the like, are known. With respect to the first method, the existence of software for service organizations and retailers to perform this method is well known. Also, with respect to the second method, data erasing devices for controlling the strength of a magnetic field applied to the spindle motor of the hard disk device and erasing data by applying a strong magnetic field to the magnetic disks is known (for example, refer to the claims, FIG. 1, and FIG. 2 of Japanese Unexamined Patent Application No. 2001-331904).
Since the object of the data erasing device disclosed in Japanese Unexamined Patent Application No. 2001-331904 is to reuse the magnetic disks, data on the magnetic disk is deleted by passing one end of the magnetic disk device through a magnetic field between permanent magnets in a state where the magnetic disk is rotated by the spindle motor.
The method of writing random data on the entire surface of the magnetic disks of the hard disk device as described above has a problem in that writing the data takes time due to the large capacity of the hard disk device, and has an additional problem in that the disposal cost increases when a service organization is asked to erase the data. On the other hand, in the data erasing device disclosed in Japanese Unexamined Patent Application No. 2001-331904 for erasing data by means of magnetic saturation, by passing the magnetic disks through a strong magnetic field, equipment for rotating the spindle motor is necessary, leading to the problem of an increase in the device size. Also, there is a problem in that if, for some reason, the spindle motor does not rotate the data will not be completely erased.
In this data erasing device disclosed in Japanese Unexamined Patent Application No. 2001-331904, consideration has not been given to erasing data with the object of preventing data leakage from the disposed hard disk device, and neither has consideration been given to reusing the magnetic disks.